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The penetration profile of water-based inks into laboratory sheets made from bleached eucalypt kraft pulp
2000 (English)Independent thesis Advanced level (professional degree), 20 credits / 30 HE creditsStudent thesis
Abstract [en]

To make paper products water repelling, a hydrophobic chemical, known as size, is added to the pulp slurry in the wet end of the paper machine. It can be shown that size prevents water from penetrating the fiber structure, by measuring the contact angle between a droplet of water and a sized paper surface. More sizing will result in higher contact angle and thus less penetration. The traditional view on the penetration of water based inks, is that the ink behaves as water in terms of penetration. Thus, it is considered that sizing has the effect of preventing water based inks from penetrating paper. However, studies made by Viet Hoang and Huy Ly at the Australian Pulp and Paper Institute, APPI, revealed that normal sizing had no effect on the penetration of water based inks. The present work was an extended study of the effect of sizing on the ink penetration profile of water based inks. It was decided to study the effect of four levels of sizing on the penetration depth of two water-based inks. As the effect of refining and pressing was also believed to have an effect on the penetration depth, three levels of each were included in the study. Pulp provided by the Australian Paper’s Maryvale mill was beaten in the Valley Beater to three different Canadian standard freeness values. Unsized and sized hand sheets were made in the Moving Belt Drainage Former and were wet pressed to three different levels. The measured paper properties were contact angle, grammage and thickness. Sheets from different refining and pressing groups were then printed in full tone with yellow Hewlett-Packard and magenta Epson inks. The ink penetration profile was then analyzed using the confocal microscope. The results show that when printing with water-based yellow and magenta inks the effect of sizing on the penetration depth was generally insignificant. This shows that water-based inks do not behave as water when penetrating the paper sheet. Thus, sizing can not be applied to prevent ink from penetrating paper. The only cases where a clear decrease in penetration, due to sizing, could be seen, was for sheets made from pulp with a low level of refining and for highly wet pressed sheets.

Place, publisher, year, edition, pages
Keyword [en]
Technology, AKD, sizing, ink, penetration
Keyword [sv]
URN: urn:nbn:se:ltu:diva-51266ISRN: LTU-EX--00/319--SELocal ID: 87b0b636-3357-404a-ad08-27bc7c60ce6fOAI: diva2:1024627
Subject / course
Student thesis, at least 30 credits
Educational program
Chemical Engineering, master's level
Validerat; 20101217 (root)Available from: 2016-10-04 Created: 2016-10-04Bibliographically approved

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